It was after dinner on an autumn night in 1849 when Abner Kealoha showed up at the Rooke House in Honolulu. His son had a high fever, and Abner had come to seek help from Dr. Rooke, who was known to receive patients who couldn’t afford to pay. The doctor had already gone to bed, but his 14-year-old daughter Emma, who had made a careful study of her father’s practice, offered her assistance. Abner agreed, and Emma prepared a mix of curative powders. The child’s fever broke—and for the first time Emma experienced the profound gratification that comes with helping the sick.

In the 1840s in Hawai‘i, most of those sick were Native Hawaiians who had no immunity to newly introduced foreign diseases. During a mid-19th-century visit to the Islands, American William Bliss observed, “The dismal coughs which I hear on every side lead me to conclude that the whole nation is affected with consumption.” His words were no exaggeration. When Captain Cook arrived in 1778, the Hawaiian population was estimated to be anywhere from 350,000 to one million. By 1848 it numbered just 90,000; and in that year epidemics of dysentery, measles, whooping cough and influenza broke out. According to one source, of the 1,500 children born that year, not one lived past age 2. By the end of 1849, the epidemics had killed another 10,000 people, and in 1853 an epidemic of smallpox killed 6,000 more. The dead numbered so many that, under threat of fine or imprisonment, able-bodied men were recruited to help bury them. Day and night, residents of Honolulu heard the creaking of the wagons that collected the corpses.

Young Emma witnessed suffering all around her. In her own life, death had already taken her schoolmate, her grand-mother and her uncle. The urgency her father had impressed on her was, she knew, glaringly real: Something had to be done before the entire Hawaiian race was lost.